Hermetic compressors are widely used, for example, in refrigeration apparatuses such as refrigerator-freezers or in air conditioners. In recent years, there is a demand for such hermetic compressors to have high efficiency and high reliability so that power consumption can be reduced.
For example, Patent Literature 1 discloses a configuration in which part of a suction hole formed in a valve plate is curved for the purpose of realizing high efficiency and high reliability of a hermetic compressor. The valve plate is provided in a manner to close an end of a cylinder. The suction hole and a discharge hole are formed in the valve plate. A communication pipe of a suction muffler is connected to the suction hole. A cooling medium gas is sucked from the communication pipe into the cylinder through the suction hole.
The suction muffler is positioned below the cylinder. The communication pipe extends upward from the suction muffler below. If the direction in which the communication pipe extends is a longitudinal direction, the cylinder is provided in a manner to extend in a transverse direction. The valve plate is positioned at the end of the cylinder. The upper end of the communication pipe is provided with a communication pipe outlet, which is formed in a manner to extend in the transverse direction. The communication pipe outlet is connected to the suction hole of the valve plate, and thereby a suction passage is formed. Accordingly, a passage for the cooling medium gas, the passage extending from the communication pipe to the suction passage (the suction passage is formed by the communication pipe outlet and the suction hole), is curved from the longitudinal direction into the transverse direction at the upper end of the communication pipe.
As shown in FIG. 11, Patent Literature 1 discloses a valve plate 80, in which a suction hole 83 is formed in a substantially U shape. A transition portion T, which is curved, is formed between an opening at the cylinder side and an opening at the communication pipe side. The transition portion T is formed such that at least part of the internal profile of a suction passage 831 is curved, and thereby a duct portion is defined. The suction passage 831 facilitates smooth transition of the cooling medium gas from a communication pipe outlet 863 to the suction hole 83, making it possible to reduce the suction resistance of the cooling medium gas. When the suction resistance is reduced, the suction mass of the cooling medium gas per unit time (i.e., a cooling medium circulation amount) increases, and thereby the efficiency of the hermetic compressor is improved.